• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.17-22
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• 1999

Since the use of porous silicon for microsensors and microactuators is in the euly stage of study, only several application devices, such as light-emitting diodes and chemical sensors have so far been demonstrated. In this paper we present an overview of the present status of porous silicon sensors and actuators research with special emphasis on the applications of chemical sensors and optical devices. The capacitive type porous silicon humidity sensors had a nonlinear capacitance-humidity characteristic and a good sensitivity at higher humidity above $40\%RH$. The porous silicon $n^+-p-n^+$ device showed a sharp increase in current when exposed to an ethanol vapor. The $p^+-PSi-n^+$ diode fabricated on porous silicon diaphragm exhibited an optical switching characteristic, opening up its utility as an optical sensor or switch. The photoluminescence (PL) spectrum, taken from porous silicon under 365 nm excitation, had a broad emission, peaked at -610 nm. The electroluminescence(EL) from ITO/PSi/In LED had a broader spectrum with a blue shifted peak at around 535nm than that of the PL.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.167-167
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• 2010

반도체는 도핑하지 않으면 대부분 n형을 나타내는 것에 반하여 GaSb는 p형을 보이는 반도체로서, 그 근원은 명확하게 규명되어 있지 않은 상태이다. GaSb의 p형 불순물인 Be은 Ga과 치환 ([$Be_{Ga}$])되므로, p형 전도의 근원으로 추정되는 잔존결함인 [$Ga_{Sb}$]와 그 복합체인 [$Ga_{Sb}-Sb_{Ga}$]와 높은 상관관계를 가질 것으로 예측된다. 본 연구에서는 Be을 도핑한 GaSb:Be 에피층을 MBE 방법으로 성장하여, PL 스펙트럼과 Hall 효과 분석을 통하여 p형 전도의 근원을 조사하였다. 도핑하지 않은 u-GaSb는 DA (deep acceptor)와 함께 A 준위를 나타낸 반면, p-GaSb:Be의 PL 스펙트럼은 Be 도핑농도가 증가함에 따라 FWHM가 줄어들면서 점차 높은 에너지 영역으로 변위하지만 농도가 가장 높은 시료에서는 PL의 FWHM가 증가하면서 에너지는 감소함이 관측되었는데, 이것은 A 피크와 Sb 관련 피크가 경쟁적으로 중첩되어 나타난 현상으로 분석된다. Hall 효과 결과는 유효 전하밀도의 증가에 따라 이동도는 감소하는 전형적인 의존성을 나타내었으며, u-GaSb의 Hall 이동도가 p-GaSb:Be의 값보다 작은 것은 u-GaSb에 잔존하는 DA에 의한 산란 때문으로 해석된다. Gaussian 형태로 분해하여 얻은 A ([$Ga_{Sb}$])와 DA ([$Ga_{Sb}-Sb_{Ga}$]) 및 Be 관련 피크로부터 특정 도핑농도 ($1.2{\times}10^{17}cm^{-3}$)의 시료를 제외한 모든 p-GaSb:Be에는 A 피크가 중첩되고 A와 Be 준위 중간에 Be과의 복합체인 중간상태(intermediate state)인 [$Be^*$]가 존재함이 관측되었는데, 특정 도핑농도에서는 [$Be_{Ga}$]이 우세하지만 더 이상 농도가 증가하면 [$Be_{Ga}$] 준위의 강도는 오히려 감소함을 관측할 수 있었다. 이것은 적정 이상의 Be을 도핑할 경우, A ([$Be_{Ga}$])와 $Be^*([Be_{Ga}-Ga_Sb}])$가 형성 ($A[Ga_{Sb}]+Be{\rightarrow}Be^*[Be_{Ga}-Ga_{Sb}]+[Be_{Ga}]$)됨을 보여 주는 중요한 결과인 것으로 분석된다. A, [Be], [$Be^*$] PL 피크 에너지는 각각 779, 787, 794 meV (오차범위 ${\pm}3\;meV$)이고, [$Be_{Ga}$]의 활성화 에너지는 ($23{\pm}3\;meV$) (20 K)임을 밝혔다.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.424-429
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• 2010

6-Alkyl-3-chromonealdehyde (2,2-dialkyl)hydrazone derivatives were synthesized by dehydration condensation. They are green-emitting materials for organic light emitting device (OLED) composed of electron acceptor of 6-alkyl-3-chromonealdehydes and electron donor of 2,2-dialkylhydrazones in a conjugated structure. The structural properties of reaction products were analyzed by FT-IR and $^1H$-NMR spectroscopy. The thermal stabilities and reactivities were measured by melting points and yields. The UV-visibles and PL properties were also determined by excitation spectra and emission spectra, respectively.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.670-674
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• 2009

3-Chromonealdehyde(2,2-disubstituted)hydrazone derivatives were synthesized by dehydration condensation. They are green-emitting materials for organic light emitting device (OLED) composed of electron acceptor of 3-chromonealdehydes and electron donor of 2,2-disubstituted hydrazones by a conjugated structure. The structural properties of reaction products were analyzed FT-IR and $^1H-NMR$ spectroscopy. The thermal stabilities and reactivities were measured by melting points and yields. The UV-visibles and PL properties can be determined by excitation spectra and emission spectra, respectively.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1705-1707
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• 2000

유기 전기발광 디스플레이 (Electroluminescence Display; ELD)는 저전압 구동, 자기발광, 경량박형, 광시야각, 빠른 응답속도 등의 장점으로 차세대 디스플레이의 후보로서 주목받고 있다. Eu complex는 610 nm 부근에서 예리한 스펙트럼의 대역폭을 가지며 붉은색의 강한 형광을 나타내는 유기화합물로 잘 알려져, 있다. 새로이 합성한 란탄계 금속착물인 $Eu(TTA)_{3}TPPO$를 발광층으로 사용하여 적색 발광의 효율을 높이기 위해 소자를 제작하였고, 이 때 구동 전압은 9 V이고 18 V에서 가장 밝은 38cd/$m^2$의 휘도를 나타내었으며 전류밀도는 20mA/$cm^2$ 이었다. 제작된 소자의 EL 스펙트럼은 615 nm로 PL 스펙트럼과 동일하게 예리한 최대 피크를 나타내었고, 순환 전압전류법을 이용하여 각 유기 물질들의 에너지 준위를 알 수 있었으며, 각각의 소자들의 에너지 밴드 다이어그램을 통하여 전기적 특성을 분석하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.703-708
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• 2009

In this paper, synthesis here Mn add to Ar any a vacuum an atomosphere $ZnGa_2O_4$ : Mn, ZnO and $Ga_2O_3$ power of 1:1 mole ratio mixture. Manufacture a close examination of oxygen a component variation luminescence a specific character reach an in fluence of $ZnGa_2O_4$ : Mn, luminescence spectrum, the surface a picture and a component ratio measurement, also an explanation of Mn site symmetry and at luminescence spectrum reach an influence from low temperature photoluminescence spectrum.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.594-598
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• 2011

We study on the preparation of green emitting materials for organic light emitting device. 3-chromonealdehyde derivatives possessing a conjugated structure, which were composed of electron acceptor of 3-chromonealdehydes and electron donor of diamines, were synthesized by dehydration-condensation process. The structural properties of reaction products were analyzed FT-IR and $^1H-NMR$ spectroscopy. The thermal stabilities and reactivities were measured by melting points and yields. The UV-visibles and PL properties can be determined by excitation spectra and emission spectra, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.6
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• pp.553-557
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• 1999

In order to investigate the optical properties of the $Al_XGa_{1-X}N/GaN$ thin film grown by metalorganic chemical vapor deposition (MOCVD) method, the photoluminescene (PL), photocurrent (PC) and persistent photoconductivity (PPC) measurements were carried out at room temperature. The band gap of the $A1_x$$Ga_{1-x}$N/GaN was determined to 3.70 eV by the PL and PC measurements. The PC measurement on the light illumination from the top of the $A1_x$$Ga_{1-x}$N/GaN thin film provides peaks at 3.70, 3.43, and around 2.2 eV. The PC spectrum by the illumination passing through from the substrate of the sample can be shown at 3.43 eV together with a broad tail band from the GaN band edge to around 2.23 eV. The photocurrent quenching and anomalous PPC decay observed in PPC measurements indicate that metastable electron states are fomed in the band gap of GaN layer to trap electrons which can be tunneled the potential barrier for long recovery time.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.141-148
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• 1999

High quality pure and Nb-doped $PbWO_{4}$ Single Crystal were grown from a 50 %~50 % mixture of Lead oxide (PbO) and Tungsten oxide $(WO_{3})$ by Czochralski method in Iridium crucible. The stoichiometric deviation correspond to the selective loss of the crystal constituents is found to be responsible for the yellowish coloration of $PbWO_{4}$. Through the X-ray powder diffraction experiment, we have investigated the lattice constant variations of each $PbWO_{4}$ crystals. We also present information on their photoluminescence (PL), optical absoption properties and Raman spectra. The temperature dependence of PL intensity and FWHM (Full Width Half Maximum) were measured in the temperature range 10 K~300 K. One observes a slight temperature dependence in the low temperature region and PL intensity decreases over 200 K by thermal quenching. The activation energy, Huang-Rhys coupling constant and inhomogenious brodenning acquired from their temperature dependence.

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.1-5
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• 2007

The 1R(Infra-Red) spectrum and PL(Photoluminescence) of the antiferromagnetic pure $MnF_2$ and the single crystal $MnF_2(1.5%\;EuF_3)$ with the rutile structures were measured. The detailed analysis of the measured PL data showed the differences of the optical property between the single crystal $MnF_2(1.5%\;EuF_3)$ and the pure $MnF_2$. It was found that the additional PL peak by the doping of the $EuF_3$ in $MnF_2$ is originated from the f-d transition of $Eu^{3+}$ from the temperature dependent intensity measurement.